The invention relates to a method for forming product stacks of folded or unfolded product blanks made of paper, chemical pulp or the like. It additionally relates to a device, in particular for carrying out the method.
In many applications, for example in the paper-processing industry or in the production of hygiene products, product blanks are produced from paper, chemical pulp, non-woven material or the like. In this case, for example when producing envelopes from paper or when producing pocket tissues or the like, the product blanks, in an unfolded state or also in a folded state, can be made of chemical pulp. Such products, in particular hygiene products, are conventionally produced in particularly large quantities, and after folding, packaged in suitably selected packaging sizes, for example in packs of 5 or 10 or even 15. For this purpose, in suitable packaging systems, suitably dimensioned product stacks, i.e. dimensioned according to the provided intended use, for example product stacks of 5 or 10, are firstly formed from the blanks and are subsequently supplied to the actual packer, where they are wrapped for example in a blown film bag or the like.
A method and a device for forming product stacks from product blanks of this type is known for example from DE 41 17 434 A1. In this known system, it is provided to place the product blanks upright on a stacking surface, and further transport subsequently takes place in stacks by means of a plurality of stack supports. This known system is intended for processing envelopes, wherein with regard to the desired exceptionally high quantities and throughputs, in relation to the design of the equipment, the load-bearing capacity of the product blanks is based on paper as the base material. In particular, envelopes have a more uniform geometry by comparison with tissue products and have greater mechanical stability than the rather soft tissue products due to the paper which is used as the base material. Due to the upright orientation of the envelopes directly before the separation thereof into the desired stack quantities, processing without format parts is thus made possible in a particularly simple manner. This means that the stack quantity can be changed, for example due to a change in the requirements in the production process whereby the number of product blanks which are to be grouped together into respective stacks is changed, in a particularly simple manner and without substituting system components. The change in the stack quantity can be carried out in particular by simply changing the point at which the separator is inserted into the series of upright envelopes. However, it is desirable to also achieve such separation without format parts in an automated stack-forming process when chemical pulp is used as the base material, as is used for example in the production and the packaging of pocket tissues, hygiene products, sanitary pads, pantyliners or the like.
The object of the invention is therefore that of providing a method of the above-mentioned type which allows, in a particularly simple and reliable manner, particularly high flexibility in the formation of the product stacks whilst also keeping the stress on the material to be processed low. In addition, a device for carrying out the method is to be provided.